The whole reason for the selfsufficientish website was to offer a place where anyone can ask, HOW DO I...? So who knows why it has taken us so long to have a HOW DO I? section, but here it is. So if you want to know how to do anything selfsufficientish then here is the place to ask.

I've a nice v. big wood burning boiler which runs a joint central heating system with a gas boiler. There is a lagged tank in the roof which open (not closed) so that we don't explode the central heating by overheating with wood. The current system doesn't have any active pumps but just uses the difference between the hot/cold water and 'thermo-siphoning' or 'gravity circulation to heat the house.
The only problem is that the furnace is huge in size, overheats the house (i.e 23+C or nothing) and we can't use the heat for other things like cooking.
We've Rayburn supreme which has a smaller footprint, enables cooking/baking and should not bake the whole house.
My question is can I directly replace the furnace with the aga or would I need a circulating pump?

I can't answer that, Andy, although I'm sure someone will, but I do have one suggestion in the meantime.

We replaced our solid fuel boiler a little while back and sized it in order to add a few more radiators (which we've done) and a 500l thermal store (which turned into a 350l TS because the plumber decided it was sufficient and OH preferred his off the cuff comment to my 6 months painstaking research - I'm not at all bitter as you can tell ). The TS is not big enough and so it overheated quite often, resulting in us running round turning on hot taps, having baths and generally being pi$$ed off, at all times of day and night.

Anyway, and the point of that preamble, is that we found an internal fan which goes in the boiler. It has a temperature setting, so it damps the fire down when it reaches that temp. It did involve replacing the boiler door for one without a vent and it does require electricity to run the fan, but it has saved us a huge amount of time, fuel and stress, and has increased the life of the TS I'm sure. It is certainly an easier and cheaper option than replacing the boiler.

Maggie

Never doubt that you can change history. You already have. Marge Piercy